1. Field of the Invention
Example embodiments of the present invention relate to semiconductor devices and methods of manufacturing the same. Other example embodiments of the present invention relate to semiconductor devices having more uniformly formed fuses, and methods of manufacturing the same.
2. Description of the Related Art
Semiconductor devices may be manufactured through four basic processes: a fabrication (hereinafter referred to as “FAB”) process, an electrical die sorting (hereinafter referred to as “EDS”) process, an assembly process and/or a test process.
During the manufacture of integrated circuits (ics) on a wafer, it may be necessary to perform several processes, including repetitively performing some of the processes. Examples of wafer processes may include diffusion, lithography, etching and/or deposition. The formation of a wafer layer, which may be capable of electrically operating, as part of a work-in-progress product is called a fab process. The finished integrated circuit is called a chip or a die.
After completing a lithography process, an EDS process may be carried on a passivation layer. The EDS process may be the last step of the FAB process. The EDS process may test the electrical properties of each of the chips constituting the wafer and/or sort out defective chips.
The EDS process may include a pre-laser test, a laser-repair process, a post-laser test and/or a back-grinding process. The pre-laser test may identify the defective chips and/or generate the sorting data. The laser-repair process may repair the identified defective chips based on the data generated from the pre-laser test. The post-laser test may re-test the repaired chips to determine if the repairing process was successful. The back-grinding process may grind down the back of the wafer by using a diamond wheel or similar instrument.
The laser-repair process may include cutting a wiring connected to a defective memory cell by irradiating a laser beam onto the wiring and/or replacing the defective memory cell with a redundancy cell built into the chip. The wiring, to be cut by the laser beam, is typically called a fuse. The fuse may be a means for electrically removing the defective memory cell when a defect is detected in a bit of the memory cell. The fuse may drive the redundancy cell that may be formed during manufacturing of the chips.
Repair may be conducted in a fuse box region of the chip. A polysilicon layer serving as a word line may be used as the fuse. In Merged DRAM and Logic (MDL) devices, the DRAM device and/or logic device may be on a single wafer to increase circuit speed and/or to reduce manufacturing costs. In MDL devices, a portion of a metal line may be used as the fuse if multilevel interconnect schemes are necessary.
FIGS. 1A to 1C are cross-sectional views illustrating a method of forming a fuse of a semiconductor device in accordance with a conventional method.
Referring to FIG. 1A, transistors (not shown) including gate electrodes, serving as word lines and/or source/drain regions, may be formed on a semiconductor substrate 10 having a memory cell region and/or a fuse box region. After forming an insulating layer (not shown) over the transistors and/or the substrate 10, a bit line 14 may be formed on the insulating layer. The bit line 14 may be electrically connected with the drain region of the transistor.
Silicon oxide may be deposited on the bit line 14 to form a first insulation interlayer 16. The first insulation interlayer 16 may be etched by a lithography process to form a contact hole 18 that may expose a portion of the bit line 14.
A conductive layer may be deposited over the contact hole 18 and/or the first insulation interlayer 16. The conductive layer may be planarized to the upper surface of the first insulation interlayer 16 to form a contact plug 20 filling up the contact hole 18. The contact plug 20 may be formed using a metal such as tungsten (W).
A first barrier layer 22, a first metal layer 24 and/or a first capping layer 26 may be deposited on the contact plug 20 and/or the first insulation interlayer 16. The first barrier layer 22 may be formed of titanium/titanium nitride (Ti/TiN). The first metal layer 24 may be formed of aluminum (Al). The first capping layer 26 may be formed of titanium/titanium nitride (Ti/TiN). The first barrier layer 22, the first metal layer 24 and/or the first capping layer may be patterned by a lithography process to form a first metal wiring 28a and/or a plurality of fuses 28b. The first metal wiring 28a may be electrically connected to the underlying bit line 14 through the contact plug 20.
Silicon oxide may be deposited on the first metal wirings 28a and/or the first insulation interlayer 16 with the fuses 28b to form a second insulation interlayer 30. The second insulation interlayer 30 may be etched by a photolithography process to form a via hole 32 that may expose a portion of the first metal wiring 28a. 
A second barrier layer 34, a second metal layer 36 and/or a second capping layer 38 may be deposited on the via hole 32 and/or the second insulation interlayer 30. The second barrier layer 34 may be formed of Ti/TiN. The second metal layer 36 may be formed of aluminum (Al). The second capping layer 38 may be formed of Ti/TiN. The second barrier layer 34, the second metal layer 36 and/or the second capping layer may be patterned by a lithography process to form a second metal wiring 40 to be electrically connected with the first metal wiring 28a through the via hole 32.
Silicon oxide may be deposited on the second metal wiring 40 and/or the second insulation interlayer 30 to form a third insulation interlayer 42. Silicon nitride may be deposited on the third insulation interlayer 42 to form a fourth insulation interlayer 44.
After coating a photoresist on the fourth insulation interlayer 44, the photoresist may be exposed and/or developed to form photoresist patterns 46 for defining the fuse box region.
Referring to FIG. 1B and FIG. 1C, using the photoresist patterns 46 as an etching mask, the fourth insulation interlayer 44, the third insulation interlayer 42 and/or the second insulation interlayer 30 may be etched to form an opening 48 that exposes the fuse box region.
The fuses 28b may be etched until the first metal layer 24 of the fuse 28b, which may be exposed by the opening 48, has a thickness of about 2,000 Å.
When performing the etching process of opening the fuse box region, it may be difficult to accurately etch the third insulation interlayer 42 and/or second insulation interlayer 30, which may be formed of silicon oxide, to a depth of about 25,000 Å at the etch rate of about 10,000 Å/min, without using an etch stop layer.
As shown in FIG. 1B, if the insulation interlayers 42 and 30 are not sufficiently etched, then the fuse 28b may be under-exposed. As a result, when cutting a fuse connected to a defective memory cell in a laser-repair step, over-cutting using a higher-energy laser beam may be necessary in order to remove the insulating layer on the fuse. An adjacent fuse (e.g., a fuse connected to a normal memory cell) may be damaged.
As shown in FIG. 1C, if the insulation interlayers 42 and 30 are over-etched in order to sufficiently expose the fuse 28b, the fuse 28b may break due to the removal of the first metal layer 24.